Hydroelectric Power
Introduced| English |
|---|
| hydroelectric/ˌhaɪdrəʊɪˈlektrɪk/ |
| reservoir/ˈrezəvwɑː/ |
| turbines/ˈtɜːbaɪnz/ |
| renewable/rɪˈnjuːəbl/ |
| floods/flʌdz/ |
Power from falling water
- A hydroelectric 水电 dam turns flowing water into electricity.
- A dam holds a river back, forming a lake called a reservoir 水库.
- When water is let through, it falls with great force.
- That falling water spins turbines to make power.
How it works
- Water high behind the dam holds stored energy.
- Open the gates and it rushes down through turbines 涡轮机.
- The spinning turbines drive generators.
- Close the gates to save the water for later.
A hydroelectric dam makes electricity from…
Water held high behind the dam falls through turbines, spinning generators to make electricity.
The benefits
- It is renewable 可再生 — the water cycle refills the river.
- It releases almost no CO2 while running.
- It is reliable: open the gates when power is needed.
- So it can back up intermittent solar and wind.
One advantage of hydropower over solar and wind is that it…
Operators release stored water when power is needed, so hydro is reliable and controllable — unlike intermittent solar and wind.
The lake of water held behind a dam is called a ____.
The reservoir stores water — and energy — until it is released through the turbines.
The costs
- The reservoir floods 淹没 land, drowning valleys and habitat.
- The dam blocks fish swimming upstream to breed.
- People living in the valley must be moved away.
- It also traps sediment that rivers normally carry downstream.
Benefit or cost of a dam?
Sort each effect of a hydroelectric dam into a benefit or a cost.
A dam can block fish from swimming upstream to breed.
A dam is a wall across the river, blocking migrating fish unless a fish ladder is built.
Select all costs of a hydroelectric dam.
Dams flood land, block fish, and displace people. But they release almost no CO2 while running.
Hydropower's great strength is control: unlike solar and wind, you can turn it up or down on demand by releasing more or less water. But that dam is also its great cost — it drowns land, walls off fish, and displaces people. It is renewable and low-carbon, yet far from harmless to the river.
Building a dam:
- Engineers wall off a river valley; water backs up into a huge reservoir, flooding farms and forest.
- Now the town downstream gets reliable, carbon-free electricity — turned up each evening as demand rises.
- But the salmon that once swam upstream to spawn hit a concrete wall, and the families whose valley is now underwater had to leave.
Hydroelectric power spins turbines with water falling from a reservoir behind a dam. Benefits: renewable, low-CO2, and reliable — controllable on demand, unlike solar and wind. Costs: the reservoir floods land and habitat, the dam blocks fish migration, and it can displace people.